Axial flow fan, range hood comprising axial flow fan and air supply equipment comprising axial flow fan

Abstract

The invention relates to the field of range hoods, and provides an axial flow fan, a range hood comprising the axial flow fan and air supply equipment comprising the axial flow fan. In the axial direction of the axial flow fan and in the direction from an inlet of the axial flow fan to an outlet of the axial flow fan, the first-stage blade assembly, the second-stage blade assembly,..., and the Kth-stage blade assembly are sequentially arranged, and in the blade assemblies of the same stage, the movable blades are arranged on the upstream of the fixed blades; along with the increase of the number of stages, the axial distance between the same-stage moving blades and the same-stage stationary blades and the axial distance between the front-stage stationary blades and the rear-stage moving blades are monotonically changed and are not completely the same, so that the noise at the inlet of the axial flow fan or the noise at the outlet of the axial flow fan can be reduced.

Description

Technical Field

[0001] The invention relates to the field of range hoods, and in particular to an axial flow fan. Background Art

[0002] Forward-intake multi-blade centrifugal fans (referred to as "centrifugal fans") are commonly used in range hoods. Centrifugal fans mainly include impellers and volutes. In order to reduce noise, the impeller diameter needs to be increased. After the impeller is added with the volute, the fan volume is further increased, thereby increasing the manufacturing and installation costs. The small space for installing range hoods in home kitchens limits the increase in the volume of centrifugal fans, resulting in limited noise reduction potential.

[0003] like Figure 1 As shown, the inlet and outlet paths of the centrifugal fan 5000' are vertical; the range hood 10000' takes in air upward from the fume hood 2000', and the centrifugal fan takes in air horizontally. The airflow is forced to turn at a right angle, which results in an unsmooth airflow path, reduces the energy efficiency of the range hood, and increases noise. Figure 1 Arrows are used to indicate the direction of airflow.

[0004] In order to improve the comprehensive performance of the range hood, there are several solutions:

[0005] (1) Use axial flow fans in range hoods. Figure 2 The housing 1' of the axial flow fan 1000' is provided with an intermediate shaft 3', the stationary blades 22' are fixed on the housing, the moving blades 21' are fixed on the rotating part 32' of the intermediate shaft, the rotating part is rotatably arranged relative to the stationary part 31' of the intermediate shaft, and the stationary part is fixed on the housing through the stationary blades, driving the rotating part to rotate, so as to drive the stationary blades to rotate and do work on the airflow. The axial flow fan does not have a volute, and the airflow enters and exits along the axial Z direction. The volume is much smaller than that of a conventional centrifugal fan, and the layout freedom in the whole machine air duct is very high, so that space can be saved to facilitate the installation of thicker sound-absorbing and sound-insulating structures; it is easy to place on the ceiling to keep the noise source away from the user; it is easy to use with a low-resistance sound-absorbing air duct. However, the axial flow fan itself has the characteristics of large flow and small pressure rise. Under the same conditions, the boosting capacity is not as good as that of the centrifugal fan. If the axial flow fan is to be used in a range hood, a higher speed is required, which makes it difficult to reduce the noise. It is also difficult for axial flow fans to increase their boost capacity by increasing their outer diameter like centrifugal fans do. This is because under the premise of the same speed, similar geometry and similar velocity triangle shape, the flow rate and pressure rise of axial flow fans are approximately quadratic with the outer diameter; while the flow rate and pressure rise of centrifugal fans are approximately linear and quadratic with the outer diameter, respectively. In addition, in order to achieve better aerodynamic performance, axial flow fans often need to use three-dimensional twisted blades. However, due to processing cost constraints, the blade shape design freedom is low, so it is usually not possible to achieve higher efficiency.

[0006] (2) Figure 3, placing the centrifugal fan on the ceiling can cleverly utilize the vertical direction of the centrifugal fan's air intake and exhaust to reduce an elbow in the exhaust duct, thereby reducing resistance and improving efficiency. In order to ensure a better overall effect, the centrifugal fan can only be installed inside the ceiling and at the bend of the original exhaust duct. The size of the centrifugal fan in the range hood is usually much larger than the size of a ceiling board, which means that multiple boards and keels on the ceiling must be removed during installation, increasing the difficulty and cost of installation. Figure 4 If the size of the centrifugal fan on the ceiling is too large, the air intake duct will inevitably move forward 4000' relative to the wall 20000', making the appearance of the range hood complicated. Figure 5 The air intake duct is close to the wall to make the range hood simple in appearance, which will lead to uneven air intake. If the size of the centrifugal fan on the ceiling is reduced, its aerodynamic performance and noise reduction performance will be reduced.

[0007] In summary, the existing range hoods have poor overall performance and are unable to meet the requirements of compact fan structure, good aerodynamic performance, low noise, and easy installation. Summary of the invention

[0008] The technical problem to be solved by the present invention is to overcome the defect of poor comprehensive performance of the fan in the range hood in the prior art, and to provide an axial flow fan and a range hood and air supply equipment including the same.

[0009] The present invention solves the above technical problems through the following technical solutions:

[0010] An axial flow fan comprises a K-level blade assembly, the blade assembly comprises two types of blades, a moving blade and a stationary blade, K is an integer and K≥2;

[0011] Along the axial direction of the axial flow fan and from the inlet of the axial flow fan to the outlet of the axial flow fan: the first-stage blade assembly, the second-stage blade assembly, ..., the K-stage blade assembly are arranged in sequence, and in the blade assemblies of the same stage, the moving blades are arranged upstream of the stationary blades;

[0012] The average axial distance between the trailing edge of the i-th stage moving blade and the leading edge of the i-th stage stationary blade is drs_i, i=1, 2, ..., K; the average axial distance between the trailing edge of the j-th stage stationary blade and the leading edge of the j+1-th stage moving blade is dsr_j, j=1, 2, ..., K-1;

[0013] As i increases, as j increases, drs_i and dsr_j change monotonically in the same direction;

[0014] When K=2, drs_1≠drs_K;

[0015] When K>2, drs_1≠drs_K and / or dsr_1≠dsr_K-1.

[0016] In this solution, in the axial flow fan, the larger the drs_i, the more evenly the fluid is mixed when it flows from the trailing edge of the same-level moving blade to the trailing edge of the same-level stationary blade, thereby improving the blade frequency abnormal sound and reducing the fluid flow noise. Similarly, the larger the dsr_j, the more evenly the fluid is mixed when it flows from the trailing edge of the previous-stage stationary blade to the leading edge of the next-stage moving blade, which can also improve the blade frequency abnormal sound and reduce the fluid flow noise.

[0017] As i increases and j increases, drs_i and dsr_j change monotonically in the same direction, and when K=2, drs_1≠drs_K, and when K>2, drs_1≠drs_K and / or dsr_1≠dsr_K-1, so that the closer to the inlet or outlet of the axial flow fan, the larger drs_i and dsr_j are:

[0018] On the one hand, when the setting is closer to the inlet of the axial flow fan, the larger drs_i and dsr_j are, the fluid is mixed more evenly at the blades closer to the inlet, and the noise generated by the fluid flow itself is smaller; and the noise generated by the fluid flow at the downstream blades, which is larger than that at the upstream blades, gradually weakens after being blocked by multiple rows of blades, thereby reducing the noise transmitted to the upstream; therefore, the noise in the upstream part of the axial flow fan, especially at the inlet, can be reduced.

[0019] On the second aspect, similar to the first aspect, when the setting is closer to the outlet of the axial flow fan, the larger drs_i and dsr_j are, the more evenly the fluid is mixed at the blades closer to the outlet, and the smaller the noise generated by the fluid flow itself; and the noise generated by the fluid flow at the upstream blades, which is relatively larger than that at the downstream blades, gradually weakens after being blocked by multiple rows of blades, thereby reducing the noise transmitted to the downstream; therefore, the noise in the downstream part of the axial flow fan, especially at the outlet, can be made smaller.

[0020] Thirdly, the axial dimension of the axial fan can be prevented from increasing while reducing the noise at the inlet or outlet of the axial fan; or, the axial dimension of the axial fan can be reduced while avoiding increasing the noise at the inlet or outlet of the axial fan.

[0021] Preferably, as i increases and as j increases, drs_i and dsr_j monotonically increase or decrease in the same direction.

[0022] In this solution, such an arrangement can avoid an increase in the axial size of the axial flow fan while further reducing the noise at the inlet or outlet of the axial flow fan; or, while avoiding an increase in the noise at the inlet or outlet of the axial flow fan, further reduce the axial size of the axial flow fan.

[0023] Preferably, dsr_j>drs_i, j=i;

[0024] And / or, dsr_j>drs_(i+1), j=i.

[0025] By setting dsr_j>drs_i and / or dsr_j>drs_(i+1), the axial spacing between the j-stage stationary blades and the j+1-stage moving blades is increased, so that the fluid is mixed more evenly when flowing from the front-stage stationary blades to the leading edge of the rear-stage moving blades, thereby reducing the overall noise of the axial flow fan.

[0026] Preferably, the moving blades at each stage have the same shape and size, and the stationary blades at each stage have the same shape and size.

[0027] In this scheme, no matter how many levels of blade components there are, the blade mold only needs two sets of molds for moving blades and stationary blades. The aerodynamic performance of the axial flow fan can be changed by increasing or decreasing the number of blade components. It has good versatility and low processing cost.

[0028] Preferably, in a single-stage blade assembly, the number of blades of the same type is greater than or equal to 19, preferably greater than or equal to 39.

[0029] In this solution, such an arrangement can make the outflow of blades at each stage more uniform and reduce noise.

[0030] Preferably, in a single-stage blade assembly, the maximum consistency of the same blade is less than or equal to 1.8, preferably less than or equal to 1.4.

[0031] In this solution, such an arrangement facilitates demoulding of the blade when it is cast.

[0032] Preferably, the blades are made of plastic or aluminum alloy.

[0033] In this solution, the plastic or aluminum alloy material is relatively soft, and the wear on the mold can be reduced when the blades are manufactured by casting; the plastic or aluminum alloy material is relatively light, and the weight of the axial flow fan can be reduced when used in the axial flow fan.

[0034] Preferably, the axial flow fan further comprises a housing and an intermediate shaft arranged in the housing, a flow channel is formed between the inner surface of the housing and the outer surface of the intermediate shaft, the blade assembly is arranged in the flow channel, and the portion of the flow channel from the leading edge of the first stage moving blade to the trailing edge of the last stage stationary blade along the axial direction is the blade flow channel;

[0035] The inner diameter and the outer diameter of the blade flow channel are constant along the axial direction.

[0036] In this solution, the inner diameter and outer diameter of the blade flow channel remain unchanged at all locations along the axial direction. On the one hand, this makes the blade flow channel structure simple and easy to process; on the other hand, it makes the blade flow channel stable and reduces noise.

[0037] Preferably, the axial flow fan further comprises a housing and an intermediate shaft arranged in the housing, a flow channel is formed between the inner surface of the housing and the outer surface of the intermediate shaft, the blade assembly is arranged in the flow channel, and the portion of the flow channel from the leading edge of the first stage moving blade to the trailing edge of the last stage stationary blade along the axial direction is the blade flow channel;

[0038] The inner diameter of the blade flow channel at the same position along the axial direction is d1, and the outer diameter is d2. The range of d1 / d2 is between 0.4 and 0.8, preferably between 0.6 and 0.7.

[0039] In this solution, the blades are arranged in the blade flow channel. By setting the hub ratio d1 / d2 of the blade flow channel, the hub ratio is large enough, so that the blade height is small enough, which is convenient for setting the curvature of the blade tip and the blade root to be smaller, and the fluid flows smoothly with low noise; the hub ratio is small enough, so that the blade height is large enough, so that the channel when the fluid flows through the blade is large enough, and the flow rate is large enough.

[0040] Preferably, the axial flow fan also includes a shell, two suspension brackets, and an intermediate shaft arranged in the shell, the intermediate shaft includes two stationary parts respectively located at both ends along the axial direction, and a rotating part located between the two stationary parts and rotating around the axial direction, the two stationary parts are respectively fixed to the shell through one of the suspension brackets, the blade assembly is axially located between the two suspension brackets, the moving blades are fixed to the rotating part, and the stationary blades are fixed to the shell.

[0041] In this solution, a front suspension bracket and a rear suspension bracket are provided to fix the two ends of the intermediate shaft to the casing, which can improve the reliability and force stability of the installation of the rotating part and the moving blades of the intermediate shaft.

[0042] Preferably, the height of a single blade is H, the average chord length is L, and H / L is ≥ 2.1, preferably ≥ 3.4;

[0043] And / or, the axial dimension of the axial flow fan is less than or equal to 300 mm.

[0044] In this solution, such an arrangement can make the blades small enough in the axial direction, so that the axial fan can be small enough in the axial direction for easy installation. If the axial fan is used in a range hood, the axial direction of the axial fan is arranged in the vertical direction, which can reduce the space occupied by the axial fan in the vertical direction; if the axial fan is installed on the ceiling, there is enough space to install the axial fan without removing the ceiling keel, so as to save installation costs.

[0045] Preferably, the tip chord length and the root chord length of the moving blade are L1 and L2 respectively, and L1 / L2 is ≥1.1, preferably ≥1.4.

[0046] In this solution, by setting L1 / L2 to be large enough, the bending degree of the tip of the moving blade is reduced, the fluid flows more smoothly here, thereby reducing the noise.

[0047] Preferably, the axial coordinates of the trailing edge of the tip and the trailing edge of the root of the moving blade are Z1 and Z2 respectively, Z1 < Z2, and the axial coordinate increases in the direction from the inlet to the outlet of the axial flow fan.

[0048] In this solution, in the same blade assembly, the trailing edge of the tip of the moving blade is inclined axially away from the trailing edge of the root in the direction away from the stationary blade, so as to increase the axial distance between the trailing edge of the tip of the moving blade and the leading edge of the stationary blade, thereby reducing the noise generated when the fluid flows from the trailing edge of the tip of the moving blade to the leading edge of the stationary blade.

[0049] Preferably, the chord length of the root of the moving blade is L2, and |Z1 - Z2| ≤ 5%L2.

[0050] Preferably, in a single-stage blade assembly, the average relative flow velocity at the outlet and the average relative flow velocity at the inlet of the same type of blade are V1 and V2 respectively, V1 / V2 ≥ 0.75, preferably ≥ 0.82.

[0051] In this solution, by setting like this, the pressure difference and the amplitude of the pressure pulsation on the blade surface can be reduced, and the load on the blade can be reduced.

[0052] Preferably, in at least one type of blade, the phases of the same type of blades at each stage around the axis are different.

[0053] In this solution, by setting the phases of the stationary blades at each stage to be the same and the phases of the moving blades at each stage to be different, during the process that the fluid flows from the upstream blade to the downstream blade and beats the downstream blade, the dynamic-static interference abnormal noise generated between the moving blade and the stationary blade in each blade assembly can be scattered, and the obvious blade frequency abnormal noise no longer appears.

[0054] Preferably, in the same type of blades at each stage, the number of blades in a single row is ZR, and the phase difference between the same type of blades in two adjacent stages around the axis is 360° / (ZR*K).

[0055] In this solution, by setting like this, the processing is convenient, and the effect of avoiding or reducing the blade frequency abnormal noise is better.

[0056] An oil fume extractor includes an axial flow fan as described in any of the above technical solutions. The inlet of the axial flow fan is the inlet of the oil fume extractor or is communicated with the inlet of the oil fume extractor, and the outlet of the axial flow fan is the outlet of the oil fume extractor or is communicated with the outlet of the oil fume extractor, drs_1 ≥ drs_2 ≥ …… ≥ drs_K, dsr_1 ≥ dsr_2 ≥ …… ≥ dsr_(K - 1).

[0057] In this solution, the axial flow fan is used in the range hood. The inlet of the axial flow fan is closer to the user than the outlet. By setting drs_1≥drs_2≥…≥drs_K and dsr_1≥dsr_2≥…≥dsr_(K-1), the noise at the inlet of the axial flow fan can be reduced, thereby reducing the noise transmitted to the user.

[0058] Preferably, the inner diameter of the axial flow fan outlet is between 160 mm and 220 mm, and preferably between 175 mm and 185 mm.

[0059] In this solution, the arrangement is such that the inner diameter of the axial flow fan outlet is close to the inner diameter of the universal smoke pipe, thereby facilitating the connection between the axial flow fan outlet and the universal smoke pipe.

[0060] An air supply device, comprising an axial flow fan as described in any of the above technical solutions, wherein the inlet of the axial flow fan is the inlet of the air supply device or is connected to the inlet of the air supply device, the outlet of the axial flow fan is the outlet of the air supply device or is connected to the outlet of the air supply device, drs_1≤drs_2≤……≤drs_K, dsr_1≤dsr_2≤……≤dsr_(K-1).

[0061] In this solution, the air supply equipment is used to supply air, and the outlet of the axial flow fan is closer to the user than the inlet. It is set that drs_1≤drs_2≤…≤drs_K, dsr_1≤dsr_2≤…≤dsr_(K-1) to reduce the noise at the outlet of the axial flow fan, thereby reducing the noise transmitted to the user.

[0062] The positive and progressive effects of the present invention are:

[0063] Using K-class to achieve the pressure rise and flow rate of axial flow fans can ensure that the aerodynamic performance of the axial flow fan is good enough while keeping the noise level of the axial flow fan low. In addition, by designing the K-class blade assembly, each row of blades will reflect and absorb the noise to a certain extent, thereby further reducing the noise. Applying K-class axial flow fans to range hoods can make the range hoods have good aerodynamic performance and low noise.

[0064] It is set that as i increases and as j increases, drs_i and dsr_j change monotonically in the same direction, and when K=2, drs_1≠drs_K, and when K>2, drs_1≠drs_K and / or dsr_1≠dsr_K-1, so that the closer to the inlet or outlet of the axial flow fan, the larger drs_i and dsr_j are, so that the noise at the inlet or outlet of the axial flow fan is smaller. In addition, while reducing the noise at the inlet or outlet of the axial flow fan, the axial size of the axial flow fan can be avoided from increasing; or, while avoiding increasing the noise at the inlet or outlet of the axial flow fan, the axial size of the axial flow fan can be reduced.

[0065] The inlet of the axial flow fan in the range hood is closer to the user than the outlet. By setting drs_i and dsr_j to be larger as they are closer to the inlet of the axial flow fan, the noise at the inlet of the axial flow fan is smaller, thereby reducing the noise transmitted to the user.

[0066] The outlet of the axial flow fan in the air supply equipment is closer to the user than the inlet. By setting drs_i and dsr_j to be larger as they are closer to the outlet of the axial flow fan, the noise at the outlet of the axial flow fan is smaller, thereby reducing the noise transmitted to the user. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 is a schematic diagram of an existing range hood;

[0068] Figure 2 Schematic diagram of an existing axial flow fan

[0069] Figure 3 is a schematic diagram of an existing range hood;

[0070] Figure 4 is a schematic diagram of an existing range hood;

[0071] Figure 5 is a schematic diagram of an existing range hood;

[0072] Figure 6 is a schematic diagram of the range hood in Example 1;

[0073] Figure 7 is a schematic diagram of the axial flow fan in Example 1;

[0074] Figure 8 This is a meridian view of the axial flow fan in Example 1;

[0075] Fig. 9 is a schematic diagram of the blade, intermediate shaft and rear suspension bracket in Example 1;

[0076] Fig.10 is a schematic diagram of the blade, intermediate shaft and rear suspension bracket in Example 1;

[0077] Fig.11 is a schematic diagram of an intermediate shaft and a rear suspension bracket in Example 1;

[0078] Fig.12 is a cross-sectional view of the intermediate shaft and the rear suspension bracket in Example 1;

[0079] Fig.13 This is a schematic diagram of the moving blade on the intermediate shaft in Example 1;

[0080] Fig.14 Schematic diagram of the moving blade in Example 1;

[0081] Fig.15 Schematic diagram of the moving blade in Example 1;

[0082] Fig.16 This is a schematic diagram of blade phases in Example 1;

[0083] Fig.17 This is a schematic diagram of the blade phase in Example 2.

[0084] Description of reference numerals:

[0085] Figure 1 to Figure 5 Tags in:

[0086] Axial flow fan 1000', housing 1', moving blades 21', stationary blades 22', intermediate shaft 3', stationary part 31', rotating part 32', rear suspension bracket 42';

[0087] Fume hood 2000', air intake duct 4000', centrifugal fan 5000', range hood 10000';

[0088] Wall 20000';

[0089] Figure 6 to Figure 17 Tags in:

[0090] Axial fan 1000;

[0091] Shell 1, front shell 11, rear shell 12;

[0092] Blade assembly 2;

[0093] Moving blade 21, first-stage moving blade 211, second-stage moving blade 212, third-stage moving blade 213;

[0094] Stationary blade 22, first-stage stationary blade 221, second-stage stationary blade 222, third-stage stationary blade 223;

[0095] Leading edge 231, trailing edge 232, blade tip 241, blade root 242;

[0096] Intermediate shaft 3;

[0097] The stationary part 31, the fairing 311, and the exhaust tail cone 312;

[0098] Rotating part 32, primary rotating part 321, secondary rotating part 322, tertiary rotating part 323, rotating shaft 34;

[0099] Suspension bracket 4, front suspension bracket 41, rear suspension bracket 42;

[0100] Blade flow channel 5;

[0101] Fume hood 2000, housing 3000;

[0102] Range hood 10000. DETAILED DESCRIPTION

[0103] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0104] Example 1

[0105] This embodiment provides a range hood 10000, Figure 6-Figure 16 is a schematic diagram of this embodiment.

[0106] like Figure 6 The range hood 10000 includes an axial flow fan 1000, a fume collecting hood 2000 and a housing 3000. The structure of the axial flow fan 1000 is as follows: Figure 7-Figure 16 An opening is formed at the bottom of the fume hood 2000 to serve as the inlet of the range hood 10000, the housing 3000 and the fume hood 2000 are fixed, the axial flow fan 1000 is installed in the housing 3000, the inlet of the axial flow fan 1000 is connected to the inlet of the range hood 10000, and the outlet of the axial flow fan 1000 forms the outlet of the range hood 10000.

[0107] In this embodiment, the length direction, width direction, and height direction of the range hood 10000 are respectively the X direction, the Y direction, and the Z direction, which are perpendicular to each other, and the Z direction is parallel to the vertical direction. In the drawings of the present invention, the Z direction is parallel to the axial direction of the axial flow fan 1000. For the convenience of the following description, the Z direction is defined as a single direction, and the arrow direction of the Z direction corresponds to the direction from the inlet to the outlet of the axial flow fan 1000, and also corresponds to the direction of the fluid flowing from upstream to downstream in the axial flow fan 1000.

[0108] In a preferred embodiment, the inner diameter of the outlet of the axial flow fan 1000 is between 160 mm and 220 mm, so that the inner diameter of the outlet of the axial flow fan 1000 is close to the inner diameter of the commonly used universal smoke pipe, thereby facilitating the connection between the outlet of the axial flow fan 1000 and the universal smoke pipe. Further, the inner diameter of the outlet of the axial flow fan 1000 is set between 175 mm and 185 mm, so that the inner diameter of the outlet of the axial flow fan 1000 is close to the inner diameter of most universal smoke pipes, further improving the convenience of connecting the axial flow fan 1000 and the smoke pipe.

[0109] In other embodiments, the shape and installation direction of the range hood 10000 can be adjusted according to the use requirements. The inlet of the axial flow fan 1000 can be set as the inlet of the range hood 10000, for example, when the fume hood 2000 is not set; or, the inlet of the axial flow fan 1000 and the inlet of the range hood 10000 can be connected. The outlet of the axial flow fan 1000 can be used as the outlet of the range hood 10000; or, the outlet of the axial flow fan 1000 and the outlet of the range hood 10000 can be connected through a pipeline.

[0110] like Figure 7-10 The axial flow fan 1000 includes a K-stage blade assembly 2, K=3. The single-stage blade assembly 2 includes two types of blades, namely a row of moving blades 21 and a row of stationary blades 22. Along the Z direction, the first-stage moving blades 211, the first-stage stationary blades 221, the second-stage moving blades 212, the second-stage stationary blades 222, the third-stage moving blades 213, and the third-stage stationary blades 223 are arranged in sequence.

[0111] In this embodiment, the pressure rise and flow rate achieved by the 1st-level axial flow fan 1000 are realized by using the K-level, so that the sound power is expected to be reduced to the original 1 / K. In this way, the axial flow fan 1000 can maintain a low noise level while ensuring that the aerodynamic performance of the axial flow fan 1000 is good enough. In addition, the K-level blade assembly 2 is designed, and each row of blades will block the noise transmission, play a certain reflection and absorption role, thereby further reducing the noise. Applying the K-level axial flow fan 1000 to the range hood 10000 can make the range hood 10000 have good aerodynamic performance and low noise.

[0112] In other embodiments, two, three or more stages of blade assemblies 2 may be provided in the axial flow fan 1000. The aerodynamic performance of the range hood 10000 may be improved by increasing the number of stages of the blade assemblies 2, and the radial dimension of the axial flow fan 1000 may be made smaller to reduce the space occupied by the axial flow fan 1000 in the X and Y directions in the kitchen.

[0113] The leading edge 231, the trailing edge 232, the blade tip 241, and the blade root 242 of the blade are well-known concepts, and can be found in Figure 14-15 The annotations in .

[0114] like Figure 8 , the average spacing between the trailing edge of the i-th stage moving blade 21 and the leading edge of the i-th stage stationary blade 22 is drs_i, i=1, 2, ..., K. As i increases, drs_i decreases, that is, the closer to the inlet of the axial flow fan 1000, the larger drs_i. K=3, the corresponding drs_i are drs_1, drs_2, drs_3, in this embodiment, drs_1>drs_2>drs_3. The average spacing can be understood as the average value of the spacing at different blade heights, Figure 8The spacing at a certain blade height is simplified and marked as the average spacing.

[0115] like Figure 8 , the average spacing along the Z direction between the trailing edge of the j-th stationary blade 22 and the leading edge of the j+1-th moving blade 21 is dsr_j, j=1, 2, ..., K-1, and as j increases, dsr_j decreases, that is, the closer to the inlet of the axial flow fan 1000, the larger dsr_j. K=3, dsr_j are dsr_1 and dsr_2 respectively, and in this embodiment, dsr_1>dsr_2. In other embodiments, if a two-stage blade assembly 2 is provided, corresponding to one dsr_j, i.e., dsr_1, it can be considered that dsr_j decreases or increases as the number of stages increases.

[0116] In the range hood 10000, the inlet of the range hood 10000 is generally closer to the user than the outlet. The noise generated closer to the inlet of the axial flow fan 1000 has a greater impact on the user. The larger drs_i is, the more evenly the fluid is mixed when it flows from the trailing edge of the moving blade 21 of the same level to the trailing edge of the stationary blade 22 of the same level, thereby improving the blade frequency abnormal sound and reducing the fluid flow noise. The closer the inlet of the range hood 10000 is to the axial flow fan 1000, the larger drs_i and dsr_j are. On the one hand, the airflow is mixed more evenly at the blades closer to the inlet of the axial flow fan, the smaller the noise generated by the airflow itself, and the smaller the noise transmitted to the user. On the other hand, although the closer the outlet of the axial flow fan 1000 is, the smaller drs_i and dsr_j are, so that the noise generated at the downstream blades is greater than the noise generated at the upstream blades, the closer to the outlet of the axial flow fan 1000, the closer to the user. The farther away, the smaller the impact of the generated noise on the user, and the closer to the outlet of the axial flow fan 1000, the greater the noise generated by the airflow. When it is transmitted to the inlet of the axial flow fan 1000, it needs to pass through more rows of blades to block, so that the noise generated by the downstream blades gradually weakens in the process of transmitting upstream, thereby reducing the noise transmitted to the user; combining these two aspects, the noise in the upstream part of the axial flow fan 1000, especially at the inlet, can be made smaller, thereby reducing the noise transmitted from the range hood 10000 to the user.

[0117] If the noise level at the inlet of the axial flow fan 1000 is kept consistent, compared with the solution of the same drs_i and the same dsr_j, in this embodiment, by setting the closer to the inlet of the axial flow fan 1000, the larger the drs_i and the larger the dsr_j, it is convenient to reduce the axial size of the axial flow fan 1000 and make the structure compact. If the axial size of the axial flow fan 1000 is kept the same, compared with the solution of the same drs_i and the same dsr_j, in this embodiment, by setting the closer to the inlet of the axial flow fan 1000, the larger the drs_i and the larger the dsr_j, the noise at the inlet of the axial flow fan 1000 can be greatly reduced. In the range hood 10000, generally, the inlet of the range hood 10000 is closer to the user than the outlet, so that the upstream blade assembly 2 in the axial flow fan 1000 is closer to the user. By setting drs_i to decrease and dsr_j to decrease, the noise transmitted to the user by the axial flow fan 1000 can be smaller, while taking into account the compact structure performance of the axial flow fan 1000, so that the range hood 1000 can take into account both the compact structure and the low noise performance.

[0118] In other embodiments, it can be set that as i increases and as j increases, drs_i and dsr_j change monotonically in the same direction; when K=2, drs_1≠drs_K; when K>2, drs_1≠drs_K and / or dsr_1≠dsr_K-1, that is, the effect of reducing the noise at the inlet or outlet of the axial flow fan 1000 can be achieved, or the axial size and noise reduction performance of the axial flow fan 1000 can be taken into account. For example, drs_1≥drs_2...≥drs_K, and dsr_1≥dsr_2...≥drs_K-1; or drs_1≤drs_2...≤drs_K, and dsr_1≤dsr_2...≤drs_K-1, can be considered that drs_i and dsr_j change monotonically in the same direction.

[0119] In other embodiments, the axial flow fan 1000 of this embodiment or other embodiments may be applied to other scenarios besides the range hood 10000.

[0120] In other embodiments, when the inlet of the axial flow fan 1000 is closer to the user than the outlet, drs_1≥drs_2≥…≥drs_K, dsr_1≥dsr_2≥…≥dsr_(K-1) can be set. When K>2, drs_1≠drs_K and / or dsr_1≠dsr_K-1, that is, the noise at the inlet of the axial flow fan 1000 can be reduced, thereby reducing the noise transmitted to the user, or the axial size and noise reduction performance of the axial flow fan 1000 can be taken into account; further, setting drs_1>drs_2>…>drs_K, dsr_1>dsr_2>…>dsr_(K-1) will have a better effect.

[0121] In other embodiments, when the outlet of the axial flow fan 1000 is closer to the user than the inlet, such as air supply equipment such as air conditioners and blowing devices, drs_1≤drs_2≤…≤drs_K, dsr_1≤dsr_2≤…≤dsr_(K-1) can be set. When K=2, drs_1≠drs_K; when K>2, drs_1≠drs_K and / or dsr_1≠dsr_K-1, so that the noise at the outlet of the axial flow fan 1000 is smaller, thereby reducing the noise transmitted to the user; further, setting drs_1<drs_2<…<drs_K, dsr_1<dsr_2<…<dsr_(K-1) has a better effect.

[0122] In other embodiments, a first-stage stationary blade or moving blade may have only one row of blades; or, a single-stage moving blade or a single-stage stationary blade may be formed by connecting multiple rows of blades in series. In this case, for a first-stage blade, the leading edge of the first row of blades in the multiple rows of blades is considered to be the leading edge of the blade of this stage, and the trailing edge of the last row of blades is considered to be the trailing edge of the blade of this stage. The blade can be understood as a blade.

[0123] In a preferred embodiment, by setting dsr_j>drs_i, j=i, that is, the axial spacing between the j-stage stationary blade 22 and the j+1-stage moving blade 21 is greater than the axial spacing between the j-stage moving blade 21 and the j-stage stationary blade 22; and / or, setting dsr_j>drs_(i+1), j=i, that is, the axial spacing between the j-stage stationary blade 22 and the j+1-stage moving blade 21 is greater than the axial spacing between the j+1-stage moving blade 21 and the j+1-stage stationary blade 22; both can increase the axial spacing between the j-stage stationary blade and the j+1-stage moving blade, so that the fluid is mixed more evenly when flowing from the front-stage stationary blade to the leading edge of the rear-stage moving blade, thereby making the overall noise of the axial flow fan smaller.

[0124] In a preferred embodiment, the shapes and sizes of the moving blades 21 at each level are the same, and the shapes and sizes of the stationary blades 22 at each level are the same. In this way, no matter how many levels of the blade assembly 2 there are, the blade mold only needs two sets of molds, the moving blade 21 and the stationary blade 22. The aerodynamic performance of the axial flow fan 1000 can be changed by increasing or decreasing the number of levels of the blade assembly 2, which has good versatility and low processing cost.

[0125] In a preferred embodiment, the number of blades in a single row can be set to be greater than or equal to 19, so that the outflow of each row of blades is more uniform and the noise is further reduced. When the number of blades in a single row is set to be greater than or equal to 39, the effect is better.

[0126] The consistency of blades is a well-known concept and can be understood as the chord length of the blades / the distance between two adjacent blades in a single row of blades. In a preferred embodiment, the maximum consistency of a single row of blades can be set to be less than or equal to 1.8, so that the blades in a single row of blades are arranged sparsely enough to facilitate demoulding when the blades are cast. When the maximum consistency of a single row of blades is set to be less than or equal to 1.4, the effect is better.

[0127] In a preferred embodiment, the blades are made of soft plastic or aluminum alloy, which can reduce wear on the mold when the blades are manufactured by casting; plastic or aluminum alloy materials are lighter, and their use in the axial flow fan 1000 can reduce the weight of the axial flow fan 1000.

[0128] like Figure 7 The housing of the axial flow fan 1000 includes a front housing 11 and a rear housing 12, and the flange of the front housing 11 and the flange of the rear housing 12 are fixedly connected.

[0129] like Figure 8 The intermediate shaft 3 of the axial flow fan 1000 is arranged in the housing 1, and a flow channel is formed between the inner surface of the housing 1 and the outer surface of the intermediate shaft 3. The blades are arranged in the flow channel. The portion of the flow channel from the leading edge of the first-stage moving blade 211 to the trailing edge of the third-stage stationary blade 223 along the Z direction is the blade flow channel 5. Figure 8 In the figure, Z_YPLD is used to indicate the range of the blade channel 5 along the Z direction. In a preferred embodiment, the inner diameter and outer diameter of each part of the blade channel 5 are the same, so that the blade channel 5 has a simple structure and is easy to process; the blade channel 5 is stable and reduces noise. The inner diameter is d1 and the outer diameter is d2. Figure 8 's annotation.

[0130] In a preferred embodiment, the hub ratio of the blade flow channel 5 is d1 / d2, ranging from 0.4 to 0.8, so that the hub ratio is large enough, so that the blade height is small enough, so that the curvature of the blade tip and the blade root is set smaller, the fluid flows smoothly, and the noise is small; the hub ratio is small enough, so that the blade height is large enough, so that the channel when the fluid flows through the blade is large enough, and the flow rate is large enough.

[0131] In a preferred embodiment, if Figure 8, the intermediate shaft 3 includes a stationary part 31, a rotating part 32, and another stationary part 31 arranged in sequence along the Z direction, and the axial flow fan 1000 also includes two suspension brackets 4, the upstream one is the front suspension bracket 41, and the downstream one is the rear suspension bracket 42. The two stationary parts 31 are fixed to the shell 1 through a suspension bracket 4 respectively, so as to be stationary relative to the shell 1. There is a gap between the stationary blades 22 fixed on the shell 1 and the intermediate shaft 3, and there is a gap between the moving blades 21 fixed on the rotating part 32 and the shell 1. The rotating part 32 is arranged to rotate relative to the two stationary parts 31 to drive the moving blades 21 to rotate and do work on the fluid. The front suspension bracket 41 and the rear suspension bracket 42 are arranged to fix the two ends of the intermediate shaft 3 on the shell 1, which can improve the reliability and force stability of the installation of the rotating part 32 and the moving blades 21 of the intermediate shaft 3. It can be understood that the axis of the axial flow fan 1000 is the axis of the rotating part 32, and the axial direction is the extension direction of the axis of the rotating part 32.

[0132] In this embodiment, a suspension bracket 4, which can also be called a group, is formed by a plurality of support plates evenly spaced around the Z direction; two stationary parts 31, the upstream one is a fairing 311, the outer surface of which is hemispherical to reduce the fluid flow resistance, and the downstream one is an exhaust tail cone 312, the tail of which is conical to facilitate the reduction of the fluid wake and reduce noise.

[0133] like Figure 11-Figure 12 The rotating part 32 includes a rotating shaft 34 and a primary rotating part 321, a secondary rotating part 322, and a tertiary rotating part 323 arranged in sequence along the Z direction. The N-stage moving blades 21 are arranged on the N-stage rotating part 32. The rotating shaft 34 is arranged in the three rotating parts 32. The two ends are respectively rotatably arranged relative to the two stationary parts 31. For example, the rotation can be achieved by connecting with bearings. The rotating shaft 34 and the three rotating parts 32 are fixedly connected. The three rotating parts 32 and the moving blades 21 can be driven to rotate by driving the rotating shaft 34 to rotate. Fig.12 There is a small spacing between adjacent suspension brackets 4 and rotating parts 32, or between two adjacent rotating parts 32 along the Z direction. Within the range allowed by the design, it can be considered that the inner diameter of the blade flow channel 5 is constant.

[0134] The blade height H, chord length, blade tip chord length L1, blade root chord length L2, and average chord length L of the blade are well-known concepts. The blade height H can be understood as the radial dimension of the blade along the axial flow fan 1000, the chord length can be understood as the length of the tangent from the leading edge to the trailing edge of the blade, the blade tip chord length L1 can be understood as the chord length at the blade tip, the blade root chord length L2 can be understood as the chord length at the blade root, and the average chord length L can be understood as the average value of the blade chord length at different blade heights. L1 and L2 can be referred to in Fig.14 's annotation.

[0135] In a preferred embodiment, H / L≥2.1, which can make the axial dimension of the blade small enough, so that the axial dimension of the axial flow fan 1000 is small enough for easy installation. Applying the axial flow fan 1000 to the range hood 10000 can reduce the space occupied by the axial flow fan 1000 in the Z direction; if the axial flow fan 1000 is installed on the ceiling, there will be enough space to install the axial flow fan 1000 without removing the ceiling keel, so as to save the installation cost. When H / L≥3.4 is set, the axial dimension of the axial flow fan 1000 can be further reduced.

[0136] In a preferred embodiment, the axial dimension of the axial flow fan 1000 can be set to be less than or equal to 300 mm, so that the axial dimension is small enough for easy installation.

[0137] In a preferred embodiment, for the moving blade 21, L1 / L2≥1.1. Setting L1 / L2 large enough makes the tip of the moving blade 21 less bent, the fluid flow more gentle here, and thus the noise is reduced. The effect is better when L1 / L2≥1.4.

[0138] Such as Fig.14 、 Fig.15 , along the Z direction, that is, from the inlet to the outlet direction of the axial flow fan 1000, the axial coordinate increases. The axial coordinate of the tip trailing edge of the moving blade 21 is Z1, and the axial coordinate of the root trailing edge of the moving blade 21 is Z2. In a preferred embodiment, for the moving blade 21, Z1<Z2 is set, so that in the same-stage blade assembly 2, the tip trailing edge of the moving blade 21 is axially inclined away from the stator blade 22 relative to the root trailing edge, so as to increase the axial distance between the tip trailing edge of the moving blade 21 and the leading edge of the stator blade 22, thereby reducing the noise generated when the fluid flows from the tip trailing edge of the moving blade 21 to the leading edge of the stator blade 22. Further, for the moving blade 21, |Z1-Z2|≤5%L2 is set to avoid the value of |Z1-Z2| in the moving blade 21 being too large, resulting in a complex blade shape.

[0139] In a preferred embodiment, the ratio V1 / V2 of the average relative flow velocity V1 at the outlet of the blade to the average relative flow velocity V2 at the inlet is V1 / V2≥0.75, so that the flow velocity difference between the suction surface and the pressure surface of the blade is small, so as to reduce the pressure difference and the amplitude of pressure pulsation on the blade surface and reduce the load of the blade. The effect is better when V1 / V2≥0.82. V1 / V2 can also be called the Dehaller number and can be obtained through simulation or experiment.

[0140] The phase of the blade around the axis can be understood as the position of the blade in the circumferential direction of the axial flow fan 1000 and can be represented by the corresponding circumferential angle. Such as Fig.16, the phases of the moving blades 21 of each stage around the Z direction are different. Specifically, the distance difference between the first-stage moving blade 211 and the second-stage moving blade 212 in the circumferential direction is A1, and the corresponding phase difference is ∠1. The distance difference between the second-stage moving blade 212 and the third-stage moving blade 213 in the circumferential direction is A2, and the corresponding phase difference is ∠2. The fluid will hit the downstream blade when it flows from the upstream blade to the downstream blade. By setting the phase difference of the moving blades 21 of each stage to be different, the dynamic and static interference noises between the moving blades 21 and the stationary blades 22 in each stage of the blade assembly 2 are dispersed, and no obvious blade frequency noises will appear.

[0141] Example 2

[0142] This embodiment provides an axial flow fan 1000, Fig.17 The difference between this embodiment and embodiment 1 mainly lies in the phase setting of the blades. The other structures of this embodiment can refer to embodiment 1.

[0143] like Fig.17 The phases of the stationary blades 22 at each stage are the same, and the phases of the moving blades 21 at each stage are different.

[0144] In a single row of moving blades 21 , the circumferential distance between two adjacent moving blades 21 is A0, and the corresponding phase difference is ∠0, ∠0=360° / ZR, where ZR is the number of the moving blades 21 in the single row.

[0145] In a preferred embodiment, ∠1=∠2=∠0 / K=360° / (ZR*K).

[0146] In other embodiments, the phases of the stationary blades 22 of each stage and / or the phases of the moving blades 21 of each stage may be set to be different, so that the dynamic and static interference noises emitted between the moving blades 21 and the stationary blades 22 in each stage of the blade assembly 2 are dispersed, and no obvious blade frequency noises appear, thereby reducing the noise of the axial flow fan 1000. When the phases of the stationary blades 22 of each stage are set to be different, the number of stationary blades 22 in a single row may be set to ZR, and the phase difference of the stationary blades 22 of two adjacent stages around the axial direction is 360° / (ZR*K).

[0147] In general, the axial flow fan 1000 provided by the present invention has the following advantages:

[0148] 1. The axial flow fan 1000 is small in size and is used in the range hood 10000. It occupies a small space and can be arranged freely and flexibly in the air duct, thus facilitating the noise reduction design. Because the axial flow fan 1000 has the characteristic of straight airflow in and out, it is very easy to stack multiple stages without bringing high complexity to the structure. When used in the range hood 10000, a multi-stage blade assembly 2 is set to distribute the pressure rise, thereby achieving a significant noise reduction.

[0149] 2. The blades of the axial flow fan 1000 are usually distorted, which brings inconvenience to processing. The present invention improves the problem of high processing cost of the axial flow fan 1000 through the following aspects:

[0150] 2-1. The moving blades 21 and the stationary blades 22 of each stage are the same. The blade mold of the entire product only needs two sets of moving blades 21 and stationary blades 22. The aerodynamic performance of the axial flow fan 1000 can be changed by increasing or decreasing the number of stages of the blade assembly 2, so that the axial flow fan 1000 can be applied to products with different performance specifications, thereby reducing processing costs;

[0151] 2-2. Use softer materials such as plastic or aluminum alloy to make blades to reduce mold wear;

[0152] 2-3. The blade consistency is set to facilitate bidirectional rotation and demoulding of the blade;

[0153] 2-4. The shapes and sizes of the moving blades 21 at each level are the same, and the shapes and sizes of the stationary blades 22 at each level are the same, so as to reduce the manufacturing cost of the axial flow fan 1000 and facilitate the increase or decrease of the number of blade assemblies to adjust the performance of the axial flow fan 1000;

[0154] 2-5. A multi-stage blade assembly 2 is provided to achieve the target pressure rise, so the load of each stage of the blade assembly 2 is lighter and the degree of blade distortion is lower, which also reduces the processing difficulty.

[0155] 3. The aerodynamic noise of the first-stage blade assembly 2 of the axial flow fan 1000 in which the range hood 10000 is provided with a multi-stage blade assembly 2 will be directly transmitted to the inlet of the range hood 10000, while the aerodynamic noise of the blade assemblies 2 of the subsequent stages will be blocked by several rows of blades before being transmitted to the inlet of the range hood 10000, and the noise transmitted from the later stages will be blocked more by the blades. Therefore, the earlier the stage, the greater the contribution to the noise felt by the user. Therefore, in the present invention, both drs_i and dsr_j decrease as the number of stages increases, so that the pulsating noise generated at the upstream blade assembly 2 is weaker, thereby reducing the overall noise felt by the user.

[0156] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. An axial flow fan, characterized in that: It includes a K-stage blade assembly, and the blade assembly includes two types of blades, moving blades and stationary blades, where K is an integer and K≥2; Axially along the axial flow fan and from the inlet of the axial flow fan to the outlet direction of the axial flow fan: the first-stage blade assembly, the second-stage blade assembly,..., the K-stage blade assembly are arranged in sequence. Among the blade assemblies of the same stage, the moving blades are arranged upstream of the stationary blades; The average axial spacing between the trailing edge of the i-th stage moving blade and the leading edge of the i-th stage stationary blade is drs_i, where i = 1, 2,..., K; the average axial spacing between the trailing edge of the j-th stage stationary blade and the leading edge of the (j + 1)-th stage moving blade is dsr_j, where j = 1, 2,..., K - 1; As i increases and as j increases, drs_i and dsr_j change monotonically in the same direction; When K = 2, drs_1 ≠ drs_K; When K > 2, drs_1 ≠ drs_K and / or dsr_1 ≠ dsr_K - 1.

2. The axial flow fan according to claim 1, characterized in that: As i increases and as j increases, drs_i and dsr_j increase or decrease monotonically in the same direction; And / or, dsr_j > drs_i, where j = i; And / or, dsr_j > drs_(i + 1), where j = i.

3. The axial flow fan according to claim 1, characterized in that: The shapes and sizes of the moving blades of each stage are the same, and the shapes and sizes of the stationary blades of each stage are the same.

4. The axial flow fan according to claim 1, characterized in that: In a single-stage blade assembly, the number of the same type of blade is greater than or equal to 19, preferably greater than or equal to 39; And / or, in a single-stage blade assembly, the maximum solidity of the same type of blade is less than or equal to 1.8, preferably less than or equal to 1.4; And / or, the material of the blade is plastic or aluminum alloy.

5. The axial flow fan according to claim 1, characterized in that: The axial flow fan further includes a housing and an intermediate shaft disposed within the housing. A flow passage is formed between the inner surface of the housing and the outer surface of the intermediate shaft. The blade assembly is disposed within the flow passage. The portion of the flow passage between the leading edge of the first-stage moving blade and the trailing edge of the last-stage stationary blade along the axial direction is the blade flow passage; The inner diameter and outer diameter of the blade flow passage are constant along the axial direction; and / or, the inner diameter at the same axial position of the blade flow passage is d1, the outer diameter is d2, and the range of d1 / d2 is between 0.4 and 0.8, preferably between 0.6 and 0.

7.

6. The axial flow fan according to claim 1, characterized in that: The axial flow fan further includes a housing, two types of suspension brackets, and an intermediate shaft disposed within the housing. The intermediate shaft includes two stationary portions located at both ends along the axial direction and a rotating portion located between the two stationary portions and rotating around the axial direction. The two stationary portions are respectively fixed to the housing by one type of suspension bracket. The blade assembly is axially located between the two types of suspension brackets. The moving blades are fixed to the rotating portion, and the stationary blades are fixed to the housing.

7. The axial flow fan according to claim 1, characterized in that: The blade height of a single type of blade is H, and the average chord length is L, where H / L≥2.1, preferably ≥3.4; And / or, the axial dimension of the axial flow fan is less than or equal to 300 mm.

8. The axial flow fan according to claim 1, characterized in that: The tip chord length and root chord length of the moving blade are L1 and L2 respectively, where L1 / L2≥1.1, preferably ≥1.

4.

9. The axial flow fan according to claim 1, characterized in that: The axial coordinates of the tip trailing edge and root trailing edge of the moving blade are Z1 and Z2 respectively, where Z1 < Z2, and the axial coordinate increases from the inlet to the outlet direction of the axial flow fan; Preferably, the blade root chord length of the moving blade is L2, and |Z1-Z2|≤5%L2.

10. The axial flow fan according to claim 1, characterized in that: The average relative flow velocity at the outlet and the average relative flow velocity at the inlet of the same blades in the single-stage blade assembly are V1 and V2 respectively, and V1 / V2 is ≥0.75, preferably ≥0.

82.

11. The axial flow fan according to claim 1, characterized in that: In at least one type of blade, the phases of the blades of the same type at different stages around the axial direction are different; Preferably, in the blades of the same type at each stage, the number of blades in a single row is ZR, and the phase difference around the axial direction between the blades of the same type in two adjacent stages is 360° / (ZR*K).

12. A range hood, characterized in that: It includes an axial flow fan as described in any one of claims 1-11, the inlet of the axial flow fan is the inlet of the range hood or is connected to the inlet of the range hood, the outlet of the axial flow fan is the outlet of the range hood or is connected to the outlet of the range hood, drs_1≥drs_2≥……≥drs_K, dsr_1≥dsr_2≥……≥dsr_(K-1).

13. The range hood according to claim 12, characterized in that: The inner diameter of the axial flow fan outlet is between 160 mm and 220 mm, preferably between 175 mm and 185 mm.

14. An air supply device, characterized in that: It includes an axial flow fan as described in any one of claims 1 to 11, the inlet of the axial flow fan is the inlet of the air supply device or is connected to the inlet of the air supply device, the outlet of the axial flow fan is the outlet of the air supply device or is connected to the outlet of the air supply device, drs_1≤drs_2≤……≤drs_K, dsr_1≤dsr_2≤……≤dsr_(K-1).

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